Multiple band frequency response controllers have applications in many fields of electronics; however, their area of primary use is in audio signal processing. When used in the audio field, these devices are usually referred to as "equalizers", as they are often used to equalize system frequency response by compensating for frequency response aberrations of other devices in the audio signal processing chain. Such equalizers usually control a number of bands of more or less fixed frequency and bandwidth, and often use slide-type controls to set individual band response. These are known as "graphic equalizers" because the positions of the slide controls graphically represent the response curve of the device.
Many graphic equalizers are commercially available. These existing designs are generally subject to the following problems: 1. The response at the center of the control band usually only approximates the desired response level, due to the often extensive interaction between the setting of one control band and the control bands surrounding it. 2. Response between the central points of the control bands often is not smooth and shows a large amount of "ripple". 3. The effective control bandwidth often tends to vary with the setting of the control. 4. The design of the device often represents a compromise between accurate response, smoothness of response, and signal-to-noise ratio.
Therefore, an object of this invention is to provide a multiple band frequency response controller capable of generating response curves of increased smoothness and accuracy.
An additional object of this invention is to provide a multiple band frequency response controller with increased signal-to-noise ratio.